The present invention relates generally to radiant energy transmission devices and, in particular, to transmission devices having opposing reflective side walls operable in a concentrative mode whereby energy incident on an entrance area is directed to and concentrated on an exit area. In a publication, Solar Energy, Vol. 16, No. 2, pages 89-95 (1974), in a publication Solar Energy Concentration, Progress Report NSF/RANN AER 75-01065 (February 1975), in a U.S. Pat. No. 3,923,381 of Winston and in prior application Ser. No. 581,613 filed May 29, 1975, there are described techniques for generating the ideal side wall contours for such a collector or transmission device. In a subsequent publication, Applied Optics, Vol. 15, No. 2, pages 291-292, February 1976, there is a described the application of the principles disclosed in the above art relating to ideal reflective side wall contour to transmitting and guiding surfaces at the interface of media of differing indices of refraction for radiant energy. To the extent these items contain "essential material" necessary to support the claims hereof or indicate background, they are expressly incorporated by reference herein.
Devices employing these principles include solid dielectric medium. By solid dielectric medium is meant an optically clear material having an index of refraction at least greater than one. Such media are particularly suited for application with photovoltaic cells and ideally are configured according to principles contained in the publication Applied Optics referred to above. The cells would be positioned at the exit aperture or exit area of the solid medium. The prior art practice has been to bond the cell to the exit area and then bond the cell to a base for the structural support of the assembly of cell and medium. Since the bulk of the solid dielectric transmission medium is closer to the entrance area and since the exit area, which is the coupled surface through which structural support is provided, is very small compared to the entrance area, only a very slight force is sufficient to break the bond at the exit area end of the assembly, making the assembly of cell and medium very fragile. Further, the differential rates of heat expansion between the medium and the cell contributes to the instability of the prior art technique.
It is therefore an object of this invention to provide an improved radiant energy direction device.
Another object of this invention is to provide an improved radiant energy concentration and collection device.
Another object of this invention is to provide a structurally improved solar collector having a solid transmission medium and a cover plate.